Preheat oven to 375 degrees. If you have an iron skillet, use it both to cook the onions on the stove and to bake the corn bread in the oven. Otherwise, use any skillet for the onions, and bake the corn bread in a greased cake pan or loaf pan.
Melt margarine in iron skillet. Cook onions until tender. In a separate bowl, make batter by mixing corn meal and sour cream, then pour that batter into the skillet with the onions. Stir onions into batter. Bake for 30 minutes.

(This recipe was contributed as part of a "Cook of the Week" feature.)